Geometrical dependences of carbon-nitrogen coupling constants. Oximes

Lichter, Robert L.; Dorman, Douglas E.; Wasylishen, Rod

doi:10.1021/ja00810a056

Cited by 55 publications

(25 citation statements)

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“…Inspection of Tables 1 and 3-4 shows that an equally good agreement between our SOPPA(CCSD) calculations and experiment is also obtained for methanal- [67,68] and ethanaloxime [67,68,69]. Therefore we are confident to discuss the substituent effects on the couplings by analyzing our results in the following sections.…”

Section: Resultssupporting

confidence: 68%

The Effect of Substituents on Indirect Nuclear Spin-Spin Coupling Constants: Methan- and Ethanimine, Methanal- and Ethanaloxime

Provasi

Aucar

Sauer

2003

IJMS

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Ab initio calculations of the spin-spin coupling constants have been carried out for methan-and ethanimine, methanal-and ethanaloxime at the level of the second order polarization propagator approximation with coupled cluster singles and doubles amplitudes (SOPPA(CCSD)) using the aug-cc-pVTZ-J basis sets. Previously we have shown that this method can reproduce quantitatively the coupling constants for methanimine; our new results for methanal-and ethanaloxime agree also very well with the measured couplings. A study of both purely geometrical and substituent effects on all coupling constants in the title compounds is presented. Analyzing the four contributions to the coupling constants we find that the stereoelectronic effect of the nitrogen lone pair on the one-bond C-H and C-C couplings as well as the corresponding effect for the geminal N-H and N-C couplings is affected strongly by the -OH substituent. For the one-bond C-N couplings we observe that the orbital paramagnetic (OP) contribution is comparable to the Fermi Contact (FC) contribution but opposite in sign and that the spin-dipolar (SD) term amounts to between 40% and 85% of the total coupling constants. Changes in the total one-bond C-N couplings caused by the -OH substituent are also almost entirely due to SD contribution.

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Section: Resultssupporting

confidence: 68%

The Effect of Substituents on Indirect Nuclear Spin-Spin Coupling Constants: Methan- and Ethanimine, Methanal- and Ethanaloxime

Provasi

Aucar

Sauer

2003

IJMS

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“…Carbon-nitrogen coupling constants have become a matter of interest concerning their signs and the question of the relative contributions of the Fermi contact term (FC), the orbital term (OB), and the spin-dipolar term (SD) 1 to the total coupling [2][3][4] . With special emphasis to these problems we wish to report the 13 C-14 N coupling constant of diazomethane (1) (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…In unsaturated systems a positive one-bond carbon-nitrogen-15 coupling constant seems to be associated only with molecules with high-energy n-orbitals (lone-pairs), such as imines, oximes, etc., whereas in molecules with no such lone-pairs (iminium ion 2 , pyridinium and quinolinium ion 2-4 ) 1 J( 13 C-15 N) seems to be negative [2][3][4] . This suggests the carbon-nitrogen-15 coupling constant in diazomethane to be negative, considering the dominant resonance forms for the description of the ground state of 1 10 .…”

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confidence: 99%

Carbon-Nitrogen Spin-Spin Coupling in Diazomethane

Runge¹,

Firl²

1976

Zeitschrift Für Naturforschung B

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“…Le carbone du groupement nitrile (6 = 1 12,4 ppm) est coup16 avec l'azote 15. La valeur de la constante observCe (7,8 Hz) est caractkristique d'un couplage 2~1 3 C~s , lorsque le noyau es! en cis de la paire libre.…”

Section: Trinzolines Diestersunclassified

“…en cis de la paire libre. Elle est incompatible avec un couplage 'Jet donc avec la structure 27 (7). Dans la mesure oh l'on compare deux carbones de m&me hybridation, il semble bien ttabli que la proximitt de la paire libre est le facteur prCpondCrant contribuant & la valeur de la constante 2~~3 C~5 N (8,9).…”

Section: Trinzolines Diestersunclassified

Évolution thermique et photochimique des triazolines résultant de l'addition des diazocomposés aux esters d'oximino-malonodinitriles, oximino-cyanoacétates et oximino-malonates de méthyle

Perrocheau¹,

Carrié²,

Fleury³

1994

Can. J. Chem.

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R e p le 23 avril 1994 JACQUES PERROCHEAU, ROBERT C& et JEAN-PIERRE FLEURY. Can. J. Chem. 72,2458Chem. 72, (1994. La thermolyse des 1,2,3-triazolines 4, 5, 6 permet l'obtention des aziridines correspondantes seulement lorsque X = Y = C0,Me et encore avec une faible rendement. Par contre la photolyse ou l'kvolution en prksence d'acide trifluoroacktique donne de bons rksultats B condition d'opkrer B une temptrature suffisamment basse. L'Ctude de la thermolyse de 4 6 montre un nouveau mode d'kvolution des 1,2,3-triazolines non encore signal6 dans la littkrature. La grande facilitk d'klimination du groupement paratoluknesulfonate ou benzoate est certainement le facteur dkterminant dans le comportement de ces composks.JACQUES F'ERROCHEAU, ROBERT C W , and JEAN-PIERRE FLEURY. Can. J. Chem. 72,2458Chem. 72, (1994.Thermolysis of 1,2,3-triazolines 4 , 5 , 6 leads to the corresponding aziridines only when X = Y = C02Me, and then with a very low yield. However, photolysis or evolution in the presence of trifluoroacetic acid gives good results when carried out at sufficiently low temperature. The thermolysis study of &6 shows a new route to 1,2,3-triazoline decomposition that has not yet been mentioned in the literature. The easy elimination of the paratoluenesulfonate or benzoate group explains this particular behaviour. Description des rCsultatsDans un travail antCrieur (I), nous avons montrC que les esters d'oximes 1, 2 et 3 rCagissent avec divers diazocomposCs pour conduire aux 1,2,3-triazolines 4-6 (Fig. 1). idines correspondantes sauf lorsque X = Y = C02Me, oh elles sont obtenues avec des rendements de 30-40%.Par contre, la photolyse en solution dans le dichloromCthane 2 -40°C conduit aux aziridines de f a~o n pratiquement quantitative. La photolyse de 4aA (X = CN, Y = CO,Me, R' = H) donne le mClange des deux aziridines diastCrCoisom&res 7aA' et 7aA" (proportions relatives 70130) (Fig. 2).Pour la triazoline 4aB (deux diastCrCoisom&res 4aB' et 4aB" dont les stCrCochimies ne sont pas attribukes) la formation des quatre aziridines diastCrCoisom&res 7aB est observte (Fig. 3). R ' R'Seule la photolyse des triazolines 4 (R = Ts) a CtC CtudiCe. La 7aB' A 7aB"" thermolyse de ces triazolines ne permet pas l'obtention des azir-

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Geometrical dependences of carbon-nitrogen coupling constants. Oximes

Cited by 55 publications

References 0 publications

The Effect of Substituents on Indirect Nuclear Spin-Spin Coupling Constants: Methan- and Ethanimine, Methanal- and Ethanaloxime

The Effect of Substituents on Indirect Nuclear Spin-Spin Coupling Constants: Methan- and Ethanimine, Methanal- and Ethanaloxime

Carbon-Nitrogen Spin-Spin Coupling in Diazomethane

Évolution thermique et photochimique des triazolines résultant de l'addition des diazocomposés aux esters d'oximino-malonodinitriles, oximino-cyanoacétates et oximino-malonates de méthyle

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